2.4

Question 1

Ante-natal screening is

Answer 1

Antenatal screening monitors health of mother and foetus and identifies risk of a disorder and may allow for a prenatal diagnosis to be given .

Question 2

Types of antenatal screening

Answer 2

Ultra sound scanning
Blood/Urine tests

Question 3

Types of ultra sound scanning

Answer 3

Dating scan
Anomaly scan

Question 4

When are dating scans used and what are they for

Answer 4

8-14 weeks into pregnancy
Dates pregnancy and due date, used with blood and urine tests

Question 5

When are anomaly scans used and what for

Answer 5

18-20 weeks into pregnancy
Checks for physical abnormalities

Question 6

Explain blood and urine tests

Answer 6

There are some chemicals that can show up in a mothers blood and urine that may indicate a problem with pregnancy/foetus. These are marker chemicals.

Question 7

What are marker chemicals

Answer 7

Chemicals that show up in mothers blood/urine indicating problem with foetus or pregnancy

Question 8

What happens if marker chemical found in urine/blood

Answer 8

Diagnostic testing carried out

Question 9

What is diagnostic testing used for

Answer 9

Diagnostic testing is used to check for genetic abnormalities such as Down’s syndrome and edwards syndrome.

Question 10

Risk of diagnostic testing

Answer 10

Miscarriage

Question 11

Types of diagnostic testing

Answer 11

Amniocentesis
CVS

Question 12

Diagnostic testing criteria is

Answer 12

Marker chemicals and ultra sounding screening indicate problem

High risk individuals (over 35, obese)

Family history / parents carriers of genetic condition

Question 13

Explain how amniocentesis carried out

Answer 13

Cells from foetus are collected from amniotic fluid

Cells grown in lab

Karyotype produced to look for chromosome structure mutations

Question 14

Explain how CVS is carried out

Answer 14

Foetal cells are collected from placenta

Karyotype instantly done from large sample of cells

Question 15

What is a Karyotype

Answer 15

A Karyotype is a picture of a cells chromosomes. It is possible to see chromosome abnormalities

Question 16

What stage of pregnancy can amniocentesis be carried out

Answer 16

14-16 weeks

Question 17

What stage of pregnancy can CVS be carried out

Answer 17

8-10 weeks

Question 18

How long does it take for amniocentesis results

Answer 18

3 weeks

Question 19

How long does it take for CVS results

Answer 19

24 hours

Question 20

Location cells collected amniocentesis

Answer 20

Amniotic fluid

Question 21

Location cells collected CVS

Answer 21

Placenta

Question 22

Is risk of miscarriage higher in CVS or amniocentesis

Answer 22

CVS

Question 23

What is genetic counselling

Answer 23

Genetic counselling examines family trees and phenotypes to determine genotypes of all family members. This helps inform prospective parents the risk of passing on genetic diseases

Question 24

What are all patterns of inheritance

Answer 24

Autosomal dominant
Autosomal recessive
Sex-linked
Incomplete dominance

Question 25

Define autosomal

Answer 25

An autosomal gene is present on chromosome numbers 1-22. It is not present on the sex chromsomes X or Y.

Question 26

Features of autosomal dominant

Answer 26

Affected person in every generation Affects males just as much as females Sufferers can be homozygous dominant or heterozygous Healthy people are homozygous recessive

Question 27

Example of autosomal dominant disease

Answer 27

Huntingtons disease

Question 28

Features of autosomal recessive

Answer 28

Can skip a generation Equal numbers of males and females affected Sufferers are homozygous recessive Carriers are heterozygous Unaffected are homozygous dominant

Question 29

Example of autosomal recessive disease

Answer 29

Cystic fibrosis

Question 30

Define sex linked

Answer 30

A sex linked gene is present only on the X chromsome. Females have 2 x chromsomes, males have 1. Mutated genes tend to be recessive.

Question 31

Features of sex linked

Answer 31

More males affected than females Affected fathers cannot pass their conditions on to their sons Genotypes written like XRxr (female) or XrY (male) It can skip a generation Unaffected males will have unaffected or carrier daughters (depending on mother)

Question 32

Example of sex linked disease

Answer 32

Haemophilia

Question 33

Define Incomplete dominance

Answer 33

Some alleles are not fully dominant or recessive. E.g. the genes that control flower colour in snapdragon plants, an allele for red (RR) and allele for white (WW) = RW (makes pink) this can be the same for some genetic diseases

Question 34

Example of incomplete dominance disease

Answer 34

Sickle cell anemia

Question 35

Features of incomplete dominance

Answer 35

Carriers (heterozygous) are partially affected More carriers than sufferers Sufferers homozygous for mutated gene Unaffected homozygous for the normal gene Males and females equally affected

Question 36

What is postnatal screening

Answer 36

Some conditions need to be tested for immediately after birth, this is to ensure infant is not fed something or given medication that may be harmful to them.

Question 37

What is PKU

Answer 37

One condition that is postnatal screened for is called PKU. It is a metabolic disorder where the body cannot break down phenylalanine, an amino acid. It is found in all proteins. If baby ingests too much protein eg I’m breast milk it can cause brain damage

Question 38

What kind of condition is PKU and how is it inherited

Answer 38

PKU is an autosomal recessive condition Both parents must be carriers to pass the condition on It cannot be predicted by antenatal screening